Y-branched wellhead assembly



. Augn ZO, 1963 F. H. CULVER 'ETAL 3,101,118

Y-BRANCHED WELLHEAD ASSEMBLY Filed Aug. 17, 1959- FIG. I

INVENTORS:

F. H. CULVER Y J. A. HAEBER E. B. L AGUCKI R. F. PERNER BY: H. 46

THEIR AGENT United States Patent Delaware Filed Aug. 17, 1959, Ser- No.834,ll5 14 Claims. (Cl. 166-75) This invention relates to equipment usedat the top of an oil or gas well and pertains more particularly to awellhead assembly adapted to be secured to the top of a well casingheadfor controlling the fluid flow from the well while providing apparatusby which the wellhead assembly can be entered vertically for work-overoperations, while at the same time a side entry into the wellheadassembly is provided so that various tools, instruments or other devicescan be circulated into the well.

A recent development in the drilling and completion of oil and gas wellshas been the drilling and completion of underwater wells wherein thewellhead assembly and casinghead may be both positioned hundreds of feetbelow the surface of water at an offshore location, one such methodbeing described in copending patent applica tion, Serial No. 830,583,filed July 30, 1959. In order to carry out maintenance or otheroperations on wells wherein the wellhead assembly is positioned aconsiderable distance below the surface of the watenmethods for carryingout these operations are being developed. One of these methods has beenclassified as a throughthe-flowline well maintenance technique. Forperforming the required operations involved in maintaining wells in thismanner, certain tools and other devices which are capable of beingpumped into and out of the wellbore through the production fluidflowline are being developed. Since these maintenance tools must bepumped into the wellbore, and since they are not able to pass around theright angle bends in the normal wellhead assembly, new types of wellheadfittings are required to carry out the proposed operations.

It is therefore a primary object of the present invention to provide awellhead assembly provided with a production fluid flowline which joinsthe wellhead assembly in a manner such that tools, instruments, or otherdevices may be pumped through the fiowline down into the well.

Another object of the present invention is to provide a wellheadassembly adapted to be positioned under water and permit the passage oftools, instruments, or other devices which cannot move through afiowline that is curved in a radius in less than from 5 to feet.

While simple well maintenance operations can be carvr-ie'd out bycirculating tools through the flowline down into the well, the moreimportant work-over operations require that the underwater wellheadassembly be entered from the top with tools passing vertically downthrough the wellhead assembly into the well. It is therefore a furtherobject of the present invention to provide an underwater wellheadassembly which selectively permits the vertical entry into the well aswell as the circulation of various devices through a substantiallyhorizontal flowline lying on the ocean floor and into the wellheadassembly and thence to pass vertically down through the well.

Another object of the present invention is to provide apparatus by whichthe vertical conduits in an underwater wellhead assembly can be closedin a manner such that tools, instruments, or other devices may becirculated up through the Well and out through a side flowline conduitof the wellhead assembly without becoming lodged within the wellheadassembly.

Theseand other objects of the present invention will be understood fromthe following description taken with regard to the drawing, wherein:

3 ,l0 l,ll8 Patented Aug. 20, 1963 "ice FIGURE 1 is a schematic viewillustrating many of the components which may be arranged as anunderwater wellhead assembly;

' FIGURE 2 is a longitudinal view of a tool diverting plug adapted tofit within the vertical bore of a wellhead assembly in accordance withthe present invention; and

:FIGURE 3 is' a view, taken partially in longitudinal cross-section ofone form of an orienting device for positioning the tool diverting plugof FIGURE 2 within the wellhead assembly of FIGURE 1.

While the wellhead assembly of the present invention is describedhereinbelow with regard to a well having two strings of productiontubing suspended therein, it will be readily apparent that the presentwellhead assembly can be modified so as to be employed on wells having asingle string of tubing therein, or wells having three or more parallelstrings of tubing suspended within a well casing.

Referring to FIGURE 1 of the drawing, a casinghead closure member 11having an annular sealing element 12 carried on its outer surface isshown as positioned on the inner sloping seating surface 13 at the topof a casiughead 14, thus closing the casinghead 14 in a fluid-tightmanner. The casinghead closure member 11 is provided with a 1 pair ofvertical conduits centrally disposed in side-by-side side conduits.

arrangement and extending vertically down through the casinghead closurell in register with a pair of strings of production tubing (not shown)suspended within the well. For purposes of illustration, it may beconsidered that the well casinghead l4 and the wellhead assembly of thepresent invention are mounted on an offshore Well and are positionedunder water.

*Fixedly secured to the'top of the casinghead closure member 11, as bybolts 17, is a master valve 18 by which the well may be shut in uponclosing of the valve 18. The valve 18 is preferably of theremotely-controlled fullopening type, that is, the gate or plugcontrolling flow within-the valve is of a type that, when open,furnishes a straight passageway through the valve ota diametersubstantially equal to that of the vertical conduits 15 and 16. For thisparticular installation the master valve 18 would be one having two flowpassageways and two closure members therein, since it is arranged toclose both of the vertical conduits l5 and 16.

=Fixedly secured to the top of the master valve 18 is a Y spool piece 21having a pair of vertical conduits 22 and 23 therethrough in register,through master valve 18, with the vertical conduits 15 and 16 in thecasinghead closure member 11.

Smooth-1y curving from the vertical conduits 22 and 23 of the Y spoolpiece 21 are a pair of side conduits 24 and 25 which branch upwardly andoutwardly through the side wall of the spool piece 21. The curvature ofthe side conduits 24 and 25 depends, to some extent, upon the length andflexibility of the tools, instruments, or other devices, to becirculated down into the well through the Thus, with the presentlydeveloped tools, the radius of curvature of the side conduits 24 and 25may be on the order of 5 to 10 feet.

The side conduits 24 and 25 are provided with flanges 26 and 27,respectively or other coupling means, for connecting control valves 30and 31 to the side conduits 24 and 25 respectively. A pair of productionllowlines 32 and 33 are connected to the other side of the controlvalves 3% and 31. The fiowl-ines 3-2 and 33 which lead to the top of thewellhead assembly eventually curve outwardly and downwardly to the oceanfloor and then run along the ocean floor to shore or to some tankpositioned offshore for collection or separation purposes. In the eventthat the sections of the production fiowlines 32 and 33 directlyconnected to the control valves 30 and 31 are metal, they should besmoothly curved in an arc of a radius no less than that which wouldpermit objects to be o) circulated therethrough into the well. It isquite apparent that whether the flowlines 32 and 33 are of a rigid orflexible material that all curves therein must have a minimum radius ofnot less than that required for circulation of objects therethrough.

From the construction of the present Wellhead assem bly it may be seenthat tools and instruments may be readily circulated down through theproduction flowlines 32, the side conduit 24, and thence throughvertical conduits 22 and down into the well. However, on circulating thetool (not shown) up from the bottom of the well, by reversing thecirculation of fluid through conduits 32 and 33, the tool would bedriven up the vertical conduit 15 and conduit 22 and become lodgedtherein, rather than sweeping out the side conduit 24 and thence throughthe production flowline 32. It therefore has been found necessary toprovide the vertical conduits 22 and 23 of the Y spool piece 21 withdiverting plugs 34 and 35 which are remov-ably positioned therein toclose the vertical conduits 22 and 23 above the side conduits 24 and 25.The lower ends 36 and 37 of the tool diverting plugs 34 and 35,respectively, are shaped in a manner such that the lower tapered facethereof forms a continuation of the inner wall of the smoothly curvedside conduits 24 and 25. That is, the lower end 37 of plug 35 is curvedin a manner so as to bend in an arc of the same radius as side conduit25, while at the same time having a concave face machined, cut, orformed so that a concave portion is curved in a radius equal to that ofthe inside of the conduits 24 and 25.

The tool diverting plugs 34 and 35 are provided with fishing heads 41}and 41 by which the plugs 34 and 35 may be removed, as by means of awire line fishing tool. The tool diverting plugs 34- and 35 are alsoprovided with suitable retractable latching or stop means in a mannerwell known to the art for fixedly positioning the plugs in place so thatwell pressure does not force them upwardly out of alignment with theside conduits 24 and 25. Retractable latching means 42 and 43 are wellknown to the art and are used on many wire line tools. One form oflatching assembly is shown on a Type S tool manufaotured by OtisEngineering Corporation and disclosed in the, Composite Catalog of OilField Equipment 196 243 edition, page 3901. The latches 42 and 43 may bewithdrawn or set in any suitable manner, as by manipulation of thefishing heads 40 and 41 with wire line or other tools. If desired, theplugs may also be provided with O-ri'ng seals 44 and 45.

One of the tool diverting plugs 35 is shown in FIGURE 2 with thelatching means 43 in its retracted position. Suitable guide means areprovided on the tool diverting plug 35 and on the interior wall of thevertical bore 23 of the Y spool piece 21 above the side conduit 25 fororienting the plug 35 to its proper position within the verical bore 23of the Y spool piece 21. Precise location of the plug 35 within theconduit 23 is necessary in order to be able to circuit tools through theside conduit 25. If a Wellhead of the present invention were to beemployed above the surface of the water, the plugs 34 and 35 could beoriented into their proper position by hand with the use of suitableorienting markings on the top of the plugs. However, where generally thewellhead assembly of: the present invention is to be positioned underwater where it is necessary to drop the plugs 34' and 35 into place orlower them by means of a wire line, it is essential that they beprovided with guide means for their proper orientation. Any suitableguide means may be employed. For example, in FIGURE 2 the tooldivertin'g plug 35 is shown as being provided with an outwardlyextending pin 46 which is preferably spring-loaded so that most or allof its length may be retracted into the body of the plug 35 as the plugdrops through a tubing string into place.

In FIGURE 3, a section of the Y spool piece 21 is shown with a portionof the vertical condiut 23 taken above the point where the side conduit25 joins the spool body. In this particular embodiment the inner bore isprovided with a sleeve 50 adapted to orient the tubing plug 35 of FIGURE2 therein. The orienting sleeve 50 is provided with a longitudinal slotor keyway 51 from which diverging shoulders 52 and 53 slant upwardly andmeet at a point 54. The pin 46 in the tool diverting plug 35 of FIGURE 2is arranged so that it projects horizontally a short distance over theshoulders 53 and 52 of the orienting sleeve 50. As the tool divertingplug 35 is lowered or dropped into the vertical conduit 23 of the spoolpiece 21, the projecting pin 46 will engage a point on either shoulder52 or 53. Thereupon, the pin 46 will ride down the shoulder 52 or 53 andcause the tool diverting plug 35 to rotate in the bore of the verticalconduit 23 until the pin 46 and the slot or keyway 51 are in verticalalignment so that the pin drops therein. In this position the curvedlower end of the tool diverting plug 35 is in register with the innercurving wall of the side conduit 25, as shown in FIGURE 1. In wellinstallations where there is no well pressure tending to force thediverting plugs 34 and 35 out of place, the pin of the guide ororienting means also serves as the latching means, preventing the plugsfrom dropping below the desired position.

In the event that an object or device, such as a packer, is to becirculatde down the Well for permanent use therein and it is not meantto be circulated back to the surface, then it is apparent that nodiverting plugs 34 and 35 are needed in the spool piece 21 at that time.

Fixedly secured to the top of the Y spool piece 21 is a control valve 56which is preferably of the identical design as the master valve 18,having dual passageways therethrough with full-opening plugs or gatestherein. This valve 56 may be known as the swabbing valve since it isopened to allow the passage of tools therethrough during swabbing of aWell. However, with the use of a control valve 56 above the spool piece21 the lower master valve 18 may be omitted in some installations withthe spool piece 21 being connected directly to the top of the casingheadclosure member 11. In such an arrangement the flow of fluid would becontrolled by valves 30, 31 and 56. Although it is preferred that thecontrol or wing valves 33' and 31 in the side conduits 24 land 25 beattached directly to spool piece 21 or located close to the Wellheadassembly, in certain installations the production flowlines 32 and 33may be connected directly to the side conduits 24 and 25 with thecontrol of valves 30 and 31 being positioned at the other ends, i.e.,the discharge ends, of the conduits 32 land 33, which may be located onland or above the surface of the Water. It is preferred, however, thatthe Wellhead assernbly of the present invention be provided with both amaster and swabbing valve 18 and 56, respectively, as well as controlvalves 30 and 31 located close to the wellhead assembly.

Fixedly secured to the top of a swabbing valve 56 is a vertical re-entryconduit having vertical conduits 58 and 59 therein which are inregister, through valve 56, With vertical conduits 22 and 23 of thespool piece 21. The vertical re-entry conduit may be closed in asuitable fluidtight manner, such, for example, as described in copendingpatent application, Serial No. 830,587, filed July 30, 1959, or may beprovided with a flexible joint whereby the major length of the re-entryconduit can be folded over the rest on the ocean floor, as described incopending patent application, Serial No. 834,096, filed Aug. 17, 1959.The well re-entry conduit 57 is shown as being provided with a pair ofwire line shiftable sleeve valves 60 and 61 for controlling the flow ofa pressure fluid through conduits 62 and 63 and thence through conduits64 and 65 to lock, or unlock, the casinghead closure member 11 to thecasinghead, as described in copending patent application, Serial No.830,587, filed July 30, 1959.

The entire wellhead assembly of the present invention is preferablycovered by a fluidtight chamber 66 to protect the component parts fromthe corrosive action of sea water and the accumulation of marine growththereon. The valves 18, 30, 31 and 56 may be either electrically,pneumatically or hydraulically actuated by any suitable valve systemwell known to the art. In this particular installation an electric cable67 is provided for conducting electric signals to energize the series ofelectrically-actuated pilot valves 70-75 which control the flow of ahydraulic pressure fluid from electrically driven pumps 76 and 77. Thepressure fluid is contained in reservoirs 78 and 79.

In the operation of the present wellhead assembly fluid may be producedfrom the well through conduits 32 and 33 with valves 30, 31 and 18 openwhile valve 56 is closed. In the event that it was desired to run aparaffin cleaning tool down through the tubing strings in the well thatwas connected to vertical conduit 15 of the casinghead closure member11, the tool (not shown) would be inserted into the conduit 32' at itsopposite end on land, or above the surface of the water, and a fluidwould be pumped in the back of the tool to force it down through conduit32, valveSti, side conduit 24-, vertical bore 22, valve 18, verticalconduit '15, and down into the tubing string (not shown). In the eventthat conduits 32 and 33 were handling production fluid from the sameproduction Zone in the well, fluid in the well could be returned upthrough conduits =16, 2,3, 25 and 33, as the tool was being pumped downthe opposite conduit. However, in the event that conduits 32 and 33 werehandling fluids from separate production formations and were not incommunication with each other within the well, the fluid already in thetubing string and in conduits 15, 22, 24 and 3-2 at the time theparaflin cleaning tool was inserted therein, would be pumped downwardlyand into the formation again during the paraffin cleaning operation.This could also be the mode of operation when the wellhead apparatus ofthe present invention was employed on a well using a single tubingstring.

If remedial work requiring the use of wire line tools was needed in thewell and it was necessary to go into the well tubing strings with toolsthat could not pass around the smoothly-curved side conduits 24 and2510f the present wellhead assembly, it would be necessary to enter thewell through the re-entry conduit 57. After controlling the Well bycirculating packers through conduits 32 and 33, 101' controlling thewell by killing it with a drilling mud pumped through the same conduits,the valve 56 would be opened by remote control from the operational baseabove the surface of the Water and a wire line tool would be sent downthrough the re-entry conduit 57 to withdraw the [tool diverting plugs 34and 35 from the spool piece 21. It would then be possible to lowerelongated sections of tool down through the re-entry conduit 57, throughspool piece 21 and the casinghead closure member 11 and thencedownwardly into the well. After the work-over operations have beencompleted and the tools withdraWn from said well may be established, andmeans for closing off the vertically-extending conduit means to maintaina full-opening path through said curved conduit means.

2. A well assembly adapted to be secured to the top of a well casingheadfor controlling the fluid flow from said well while providing dualconduit means selectively permitting the vertical entry of devices intothe well as well as the circulation of devices into a well, saidwellhead assembly comprising a casinghead closure connected to said wellcasinghead and having vertical conduit means there- .through, a spoolpiece secured to said casinghead closure, said spool piece havingvertical conduit means therethrough in register with the verticalconduit means in said casinghead closure, smoothly-curved side conduitmeans branching upwardly and outwardly through the side wall of saidspool piece from the vertical conduit means therein, vertical conduitclosure means carried by said spool piece for closing the verticalconduit means thereof, second independent conduit means through saidcasinghead closure in communication between the interior of the well andthe space outside thereof, said vertical conduit means and saidindependent conduit means adapted to communicate through separate wellpipe strings with each other within the well, whereby well devices maybe circulated into and out of said well through said smoothly-curvedside conduit means, and vertical re-entry conduit means secured to thetop of said wellhead assembly and in register with the vertical conduitmeans of said spool piece.

3. A wellhead assembly adapted to be secured to the top of a wellcasinghead for controlling the fluid flow from said Well while providingdual conduit means selectively permitting the vertical entry of devicesinto the well as well as the circulation of devices into a well, saidwellhead assembly comprising a casinghead closure connected to at leastone producing formation, said assembly including said well casingheadand having vertical conduit means therethrough, a spool piece secured tothe top of said casinghead closure, said spool piece having verticalconduit means therethrough in register with the vertical conduit meansin said casinghead closure, smoothly-curved side conduit means branchingupwardly and outwardly through the side wall of said spool piece fromthe vertical conduit means therein, removable plug means closing thevertical conduit means in said spool piece above the side conduit meansthereof, the lower end of said plug means being shaped so that the lowerface thereof forms a continuation of the inner wall of thesmoothly-curved side conduit means, full-opening valve means secured tothe top of said spool piece for closing the vertical conduit meansthereof, second independent conduit means through said casingheadclosure in communication between the interior of the well and the spaceoutside thereof, said vertical conduit means and said independentconduit means adapted to communicate through separate well pipe stringswith each other within the well, whereby well devices may be circulatedinto and out of said well through said smoothlyculrved side conduitmean-s, and vertical re-entry conduit means secured to the top of saidvalve means and in regsister therethrough with the vertical conduitmeans of said spool piece.

4. A wellhead assembly adapted to be secured to the top of a wellcasinghead for controlling the fluid flow from said well while providingdual conduit means selectively permitting the vertical entry of devicesinto the well as well as the circulation of devices into a well, saidwellhead assembly comprising a casinghead closure connected to said wellcasinghead and having vertical conduit means therethrou-gh, a spoolpiece secured to the top of said casinghead closure, said spool piecehaving vertical conduit means therethrough in register with the verticalconduit means in said casinghead closure, smoothly-curved side conduitmeans branching upwardly and outwardly through the side wall of saidspool piece from the vertical conduit means therein, removable plugmeans closing the vertical conduit means in said spoolpieceabove theside conduit means thereof, the lower end of said plug means beingshaped so that the lower face thereof forms a continuation of the innerwall of the smoothly-curved side conduit means, first and second guidemeans, one of said means carried by the plug means and the other on theinner wall of the vertical conduit means of said spool piece whereby theengagement of said first guide means with said second guide means uponentry of said plug means into said vertical conduit means of said spoolpiece causes said plug means to rotate therein until the lower endthereof is curved to register with the inner curving wall of said sideconduit means, full-opening valve means secured to the top of said spoolpiece for closing the vertical conduit means thereof, second independentconduit means through said oasinghead closure in communication betweenthe interior of the well and the space outside thereof, said verticalconduit means and said independent conduit means adapted to communicatethrough separate Well pipe strings with each other within the well,whereby well devices may be circulated into and out of said well throughsaid smoothly-curved side conduit means, and vertical re-entry conduitmeans secured to the top of said valve means and in registertherethrough with the vertical conduit means of said spool piece.

5. A wellhead assembly adapted to be secured to the top of a welloasinghead for controlling the fluid flow from said Well while providingdual conduit means selectively permitting the vertical entry of devicesinto the well as well as the circulation of devices into a well, saidwellhead assembly comprising a oasinghead closure connected to said welloasinghead and having vertical conduit means therethrough, a spool piecesecured to the top of said casinghead closure, said spool piece havingvertical conduit means therethrou-gh in register with the verticalconduit means in said oasinghead closure, smoothly-curved side conduitmeans branching upwardly and outwardly through the side wall of saidspool piece from the vertical conduit means therein, removable plugmeans closing the vertical conduit means in said spool piece above theside conduit means thereof, the lower end of said plug means beingshaped so that the lower face thereof forms a continuation of the innerwall of the smoothly-curved side conduit means, fishing head means forinserting said plug means into the vertical conduit means of said spoolpiece and removing it therefrom, latch means in engagement between saidplug means and said spool piece for fixedly positioning said plug meanstherein, registering first and second guide means, one of said meanscarried by the plug means and the other on the inner wall of thevertical conduit means of said spool piece whereby the engagement ofsaid first guide means with said second guide means upon entry of saidplug means into said vertical conduit means of said spool piece causessaid plug means to rotate therein until the lower end thereof is curvedto register with the inner curving wall of said side conduit means,full-opening valve means secured to the top of said spool piece forclosing the vertical conduit means thereof, second independent conduitmeans through said oasinghead closure in communication between theinterior of the well and the space outside thereof, said verticalconduit means and said independent conduit means adapted to communicatethrough separate well pipe strings with each other within the Well,whereby well devices may be circulated into and out of said well throughsaid smoothly-curved side conduit means, and vertical re-entry conduitmeans secured to the top of said third valve means and in registertherethrough with the vertical conduit means of said spool 1ece. p 6. Awellhead assembly adapted to be secured to the top of a well oasingheadfor controlling the fluid flow from said well while providing du-alconduit means selectively permitting the vertical entry of devices intothe well as well as the circulation of devices into a well, saidwellhead assembly comprising a casinghead closure connected to said Wellcasinghead and having vertical conduit means therethrough, a spool piecesecured to the top of said cars inghead closure, said spool piece havingvertical conduit means therethrough in register with the verticalconduit means in said oasinghead closure, smoothly-curved side conduitmeans branching upwardly and outwardly through the side wall of saidspool piece from the vertical conduit means therein, first valve meansin said side conduit means for controlling the fluid flow therethrough,removable plug means closing the vertical conduit means in said spoolpiece above the side conduit means thereof, the lower end of said plugmeans being shaped so that the lower face thereof forms a continuationof the inner wall of the smoothly-curved side conduit means, fishinghead means for inserting said plug means into the vertical conduit meansof said spool piece and removing it therefrom, registering first andsecond guide means, one of said means carried by the plug means and theother on the inner wall of the vertical conduit means of said spoolpiece for orienting said plug means therein whereby the lower endthereof is curved to register with the inner curving wall of said sideconduit means, full-opening second valve means secured to the top ofsaid spool piece for closing the vertical conduit means thereof, secondindependent conduit means through said oasinghead closure incommunication between the interior of the well and the space outsidethereof, said vertical conduit means and said independent conduit meansadapted to communicate through separate Well pipe strings with eachother within the well, whereby well devices may be circulated into andout of said well through said srnbothlycurved side conduit means, andvertical re-entry conduit means secured to the top of said second valvemeans and in register therethrough with the vertical conduit means ofsaid spool piece.

7. Awellhead assembly adapted to be secured to the top of a welloasinghead for controlling the fiuid flow from said well while providingdual conduit means selectively permitting the vertical entry of devicesinto the well as well as the circulation of devices into a well, saidwellhead assembly comprising a oasinghead closure connected to said wellcasinghead and having vertical conduit means therethrough, firstfull-opening valve means secured to the top of said casinghead forclosing the conduit means therein, a spool piece secured'to the top ofsaid first valve means, said spool piece having vertical conduit meanstherethrough in register through said first valve means with thevertical conduit means in said casinghead closure, smoothly-curved sideconduit means branching upwardly and outwardly through the side wall ofsaid spool piece from the vertical conduit means therein, second valvemeans in said side conduit means for controlling the fluid flowtherethrough, removable plug means closing the vertical conduit means insaid spool piece above the side conduit means thereof, the lower end ofsaid plug mean-s being shaped so that the lower face thereof forms acontinuation of the inner wall of the smoothly-curved side conduitmeans, fishing head means for inserting said plug means into thevertical conduit means of said spool piece and removing it therefrom,latch means in engagement between said plug means and said spool piecefor fixedly positioning said plug means therein, registering pin meansand guide means, one of said means carried by the plug means and theother on the inner wall of the vertical conduit means of said spoolpiece for orienting said plug means therein whereby the lower endthereof is curved to register with the inner curving wall of said sideconduit means, full-opening third valve means secured to the top of saidspool piece for closing the vertical conduit means thereof, secondindependent conduit means through said casinghead closure incommunication between the interior of the well and the space outsidethereof, said vertical conduit means and said independent conduit meansadapted to communicate through separate well pipe strings with eachother within the well, whereby well devices may be circulated' into andout of said well through said smoothlycurved side conduit means, andvertical re-entry conduit means secured to the top of said third valvemeans and in register therethrough with the vertical conduit means ofsaid spool piece.

8. A wellhead for underwater wells. including at least one unitarymember including conduit means adapted to extend vertically, and acurved flow conduit means smoothly branching upwardly and outwardly fromsaid vertically-extending conduit means along a curve having a radiussuch that a well device can be pumped therethrough, and second conduitmeans through said unitary member adapted to communicate in the wellwith said curving conduit means, and means fior closing oil? thevertically-extending conduit means in said unitary member to maintain afull opening path through said curved flow conduit means.

9. A wellhead for an underwater well including at least one unitarymember including first conduit means adapted to extend vertically, andcurved flow conduit means smoothly branching upwardly and outwardly fromsaid vertically-extending conduit means, the lower end of said firstconduit means adapted to communicate through a first well pipe stringwith the interior of the well, means for closing oil thevertically-extending conduit means in said unitary member to maintain atoll opening path through said curved flow conduit means and into saidwell, and second independent conduit means in said wellhead adapted tocommunicate through a second well pipe string with the interior of thewell and with said first pipe string, whereby well devices may becirculated into and out of said well through said curved flow conduitmeans.

10. The apparatus of claim 9 including closure means for closing saidsecond conduit means.

11. The apparatus of claim 9 wherein said wellhead system is removablysecured to the top of a well having a well casing and a tubingproduction string in communication with the producing formation of thewell, said curved conduit means being in communication with the tubingstring and said second conduit means in communication with the interiorof said casing.

12. The apparatus of claim 9 wherein said wellhead system is removablysecured to the top of a well having a well casing and a pair of tubingstrings therein in normal open communication with the producingliormation of the well, said curved conduit means and said secondconduit means being in communication with separate tubing strings insaid well.

13. A wellhead assembly adapted to be secured to the top of a welleasinghead for controlling the fluid flow from said well while providingdual conduit means selectively permitting the vertical entry of devicesinto the well as well as the circulation of :devices into a well, saidwellhead assembly comprising a casinghe-ad closure connecti-ble to saidwell casinghead and having a plurality of conduit means therethrough, atleast one of said conduit means being vertical conduit means, a tubingstring in said well in register with the one vertical conduit means insaid casinglhead closure and in communication with a production zone ofthe well, smoothly-curved side conduit means branching upwardly andoutwardly through the side wall of said closure from the verticalconduit means therein, another cl said conduit means being incommunication through said closure between the same production zone inthe interior of a well and the outside thereof whereby well devices maybe circulated into and out of said well through said curved side conduitmeans, and conduit closure means co-nnectible to said closure forclosing at least the vertical conduit means thereof above the branchingconduit means.

14. A wellhead assembly adapted to be secured to the top of a wellcasinghead for controlling the fluid flow from said well while providingdual conduit means selectively permitting the vertical entry of [devicesinto the well as well as the circulation of devices into a well, saidwellhead assembly comprising a oasinghead closure connectible to saidwell casinghead and having a pair of vertical conduit meanstherethrough, and having smoothly-curved side conduit means branchingupwardly and outwardly through the side wall thereof [from at least oneof the vertical conduit means therein, said pair of vertical conduitmeans adapted to communicate through a pair of well pipe strings incommunication with each other within the well, whereby well devices maybe circulated into and out of said well through said curved side conduitmeans, and vertical conduit closure means carried by said closure forclosing at least the vertical conduit means thereof above the branchingconduit means, and vertical re-entry conduit means carried in the top ofsaid wellhead assembly and in register with the vertical conduit meansof said casinghead closure.

References Cited in the file of this patent UNITED STATES PATENTS Re.19,047 Hindcnlite-r I an. 16, 1934 399,747 Edwards Mar. 19, 18891,851,319 McCoy et al. Mar. 29, 1932 2,532,341 Shannon Dec. 5, 19502,590,688 Crain Mar. 25, 1952 2,854,215 Cox et al. Sept. 30, 19582,859,773 Wallace Nov. 11, 1958 2,862,560 Bostocket et al Dec. 2, 19582,874,784 Baker et al. L Feb. 24, 1959 2,889,886 Gould June 9, 19592,903,066 Brown Sept. 8, 1959 3,012,608 McLaren Dec. 12, 1961

1. A WELLHEAD SYSTEM ADAPTED TO BE ARRANGED AT THE TOP OF A WELL CASINGEXTENDING INTO THE GROUND AND TRANVERSING AT LEAST ONE PRODUCINGFORMATION, SAID ASSEMBLY INCLUDING FIRST CONDUIT MEANS ADAPTED TO EXTENDVERTICALLY FROM SAID WELL CASING AND CURVED CONDUIT MEANS BRANCHING FROMSAID VERTICALLY-EXTENDING CONDUIT MEANS, SECOND CONDUIT MEANS IN SAIDWELLHEAD SYSTEM IN COMMUNICATION BETWEEN THE INTERIOR OF THE WELL ANDTHE SPACE OUTSIDE THEREOF, SAID FIRST AND SECOND CONDUIT MEANS BEINGADAPTED TO BE IN COMMUNICATION WITH EACH OTHER WITHIN THE WELL WHEREBY ACIRCULATION PATH THROUGH THE WELLHEAD SYSTEM AND TO AND FROM SAID WELLMAY BE ESTABLISHED, AND MEANS FOR CLOSING OFF THE VERTICALLY-EXTENDINGCONDUIT MEANS TO MAINTAIN A FULL-OPENING PATH THROUGH SAID CURVEDCONDUIT MEANS.